A major preventive health concern for adolescents is the reduction of sexual behavior that can lead to HIV, other sexually transmitted diseases (STDs), and unwanted pregnancies. To prevent these outcomes, some high schools have established condom availability programs on their campuses. A present, there is no body of research on such programs, yet there has been much speculation about their likely impact. This study will address the following questions: (1) How prevalent are specific risk-associated sexual behaviors and risk-reduction behaviors, and what factors predict these behaviors; (2) How do adolescents' knowledge, motivation, and behavioral skills relate to their actual and expected future risk- associated sexual behaviors and risk-reduction behaviors; (3) How much do adolescents communicate about sexual matters with parents, friends, doctors, teachers and others; (4) What are the effects of a school-based condom availability program on risk-associated sexual behaviors and condom use. These questions will be addressed by analyzing data that come from a pre- post evaluation of a school-based condom availability program. Data from 2,031 9th through 12th graders in one school district were collected by means of an anonymous, self-administered questionnaire carried out in April 1992, just before the introduction of a program that provides all students with virtually unrestricted access to condoms. A one-year follow-up study of students are planned for this spring. Respondent- generated codes will be used to match otherwise anonymous records across survey waves. Analyses will use multivariate regression techniques to develop explanatory models of changes in behavior over time and to assess whether they are plausibly related to the condom program. Results should be useful to public health officials, health care providers, educators, and policymakers in developing effective interventions to prevent HIV, other STDs, and unwanted pregnancies among adolescents.